Do not pickle caches of toric varieties
tutorial: Update URL
tutorial: typos
tutorial: update links
Replaced more private_variables by cached_method to enable pickling of ToricVarieties.
Tietze Graph constructor
Szekeres Snark Graph constructor
Watkins Snark graph constructor
Blanusa Snarks graph constructors
Fixing a stupid mistake
Broken link in groups catalog doc
Add affine groups to groups.<tab>
Move QuaternionMatrixGroupGF3 from groups.misc to groups.matrix
Additions to groups.misc : AdditiveAbelian, Free, Braid, SemimonomialTransformation
trac #15503: DegreeSequences(n) returns false positive
trac #15054: rebase on 6.1.beta0
trac #15054: reviewer's comments
Trac #15054: Some snarks graph constructors

Some snarks missing from #9136.

* Tietze Snark : http://en.wikipedia.org/wiki/Tietze's_graph
* Szekeres Snarks : http://en.wikipedia.org/wiki/Szekeres_snark
* Watkins Snark : http://en.wikipedia.org/wiki/Watkins_snark
* Blanusa Snarks : http://en.wikipedia.org/wiki/Blanusa_snarks

URL: http://trac.sagemath.org/15054
Reported by: ncohen
Ticket author(s): Nathann Cohen
Reviewer(s): Frédéric Chapoton
Trac #15503: DegreeSequences(n) returns false positive

From google spreadsheet which no one reads `X-(`

{{{
[2,2,2,2,1,1,1] in DegreeSequences(7)
}}}

returns "true."

URL: http://trac.sagemath.org/15503
Reported by: ppurka
Ticket author(s): Nathann Cohen
Reviewer(s): Punarbasu Purkayastha
Trac #15368: Some cleanup in groups.<tab>

Following the discussion at https://groups.google.com/d/msg/sage-
devel/tyAxhqxk3ZI/SuBg2Ukwwj4J

I was about to say what this patch does, then noticed that it would
naturally appear on the ticket as the commit messages of the new branch
`:-)`

The reference manual page for groups looks like it could be reordered
and made cleaner, but I know so few about groups that I am sure I would
do it all wrong if I gave it a try `^^;`

Nathann

URL: http://trac.sagemath.org/15368
Reported by: ncohen
Ticket author(s): Nathann Cohen
Reviewer(s): Volker Braun